I think you are paranoid. I would go to a doctor though.

You are NOT paranoid. I have the same problem. What you have is most likely Premature Atrial Contractions (PAC's) or Premature Ventrical Contractions (PVC's) which feels like your heart stops for a second (it doesn't stop!). When you burb, some acid can come up your esophagus and as it irritates the lining of the esophagus, it stimulates the vagal nerve, which in turn stimulates the heart, making it have PAC (Most likely) or PVC (less likely). Get checked for reflux (even if you don't feel heart burn).